Analytical solution for tunnelling-induced response of an overlying pipeline considering gap formation

Soil-pipeline separation due to tunnelling has been certainly substantiated in previous model tests. However, this phenomenon has seldom been considered in current analytical solutions. This study formulates a tensionless Winkler solution that could make allowance for gap formation in soil-pipeline interaction analyses. The solution is validated by comparisons with existing experimental measure-ments and two recognized analytical solutions. Also, its advantage over an existing Winkler solution is addressed. Further parametric studies reveal that the effects of gap formation on the response of a pipeline rely largely on the tunnel volume loss and the pipeline's bending stiffness and burial depth. In general, a pipeline's bending moments and subgrade reaction forces are more susceptible than its deflections to the gap formation.